Background: The availability of minimal access instrumentation and endoscopic visualization has revolutionized the field of minimally invasive skull base surgery. The transorbital endoscopic approach using an eyelid incision has been proposed as a new minimally invasive technique for the treatment of skull base pathology, mostly extradural tumors. Our study aims to evaluate the anatomical aspects and potential role of the transorbital endoscopic approach for exposure of the sylvian fissure, middle cerebral artery and crural cistern.

Methods: An anatomical dissection was performed in four freshly injected cadaver heads (8 orbits) using 0- and 30-degree endoscopes. First, an endoscopic endonasal medial orbital decompression was done to facilitate medial retraction of the orbit. An endoscopic transorbital approach through an eyelid incision, with drilling of the posterior wall of the orbit and lesser sphenoidal wing, was then performed to expose the sylvian fissure and crural cisterns. A stepwise anatomical description of the approach and visualized anatomy is detailed.

Results: A superior eyelid incision followed by orbital retraction provided a surgical window of approximately 1.2 cm (range 1.0-1.5 cm) for endoscopic transorbital dissection. The superior (SOF) and inferior (IOF) orbital fissures represent the medial limits of the approach and are identified in the initial part of the procedure. Drilling of the orbital roof (lateral and superior to the SOF), greater sphenoidal wing (lateral to the SOF and IOF) and lesser sphenoidal wing exposed the anterior and middle fossa dura. A square-shaped dural opening provided visualization of the posterior orbital gyri, sylvian fissure and temporal pole. Intradural dissection allowed exposure of the sphenoidal portion of the sylvian fissure, M1, MCA bifurcation and M2 branches and lenticulostriate perforators. Dissection of the medial aspect of the sylvian and carotid cisterns with a 30-degree endoscope allowed exposure of the mesial temporal lobe and crural cistern.

Conclusions: The transorbital endoscopic approach allows successful exposure of the sphenoidal portion of the sylvian fissure and M1 and M2 segments of the middle cerebral artery. Angled endoscopes may provide visualization of the mesial temporal lobe and crural cistern. Although our anatomical study demonstrates the feasibility of intradural dissection and closure via an endoscopic transorbital approach, further studies are necessary to evaluate its role in the clinical scenario.

Background: Anterior and posterior ethmoid arteries supply the paranasal sinuses, septum, and lateral nasal wall. Precise identification of these arteries is important during anterior skull base procedures, endoscopic sinus surgery, and ligation of ethmoid arteries for epistaxis refractory to standard treatment. There is controversy in the literature regarding the prevalence of supernumerary ethmoid arteries.

Objective: This study examined the prevalence of supernumerary ethmoid arteries by using direct visualization after transorbital endoscopic dissection.

Methods: Nineteen cadaveric specimens were evaluated by using a superior lid crease (blepharoplasty) incision and an endoscopic approach to the medial orbital wall. Ethmoid arteries were identified as they pierced the lamina papyracea coplanar with the skull base and optic nerve. The distances from the anterior lacrimal crest to the ethmoid arteries and optic nerve were measured with a surgical ruler under endoscopic guidance.

Results: Thirty-eight cadaveric orbits were measured. Overall, there were three or more ethmoid arteries (including anterior and posterior arteries) in 58% of orbits, with 8% of the total sample that contained four or more ethmoid arteries. The average number of ethmoid arteries was 2.7. Bilateral supernumerary ethmoid arteries were noted in 42% of the specimens. The distance between the anterior lacrimal crest and the anterior ethmoid, posterior ethmoid, and optic nerve averaged 20, 35, and 41 mm, respectively. The average distance to the supernumerary or middle ethmoid artery was 29 mm.

Conclusion: This study found supernumerary ethmoid arteries in 58% of cadaveric specimens, a prevalence much higher than previously reported. Recognition of these additional vessels may improve safety during endoscopic sinus surgery and skull base surgery, and may permit more effective ligation for refractory epistaxis originating from the ethmoid system.

Objective To design and assess the quality of a novel lateral retrocanthal endoscopic approach to the lateral cavernous sinus. Design Computer modeling software was used to optimize the geometry of the surgical pathway, which was confirmed on cadaver specimens. We calculated trajectories and surgically accessible areas to the middle fossa while applying a constraint on the amount of soft tissue retraction. Setting Virtual computer model to simulate the surgical approach and cadaver laboratory. Participants The authors. Main Outcome Measures Adequate surgical access to the lateral cavernous sinus and adjacent regions as determined by operations on the cadaver specimens. Additionally, geometric limitations were imposed as determined by the model so that retraction on soft tissue structures was maintained at a clinically safe distance. Results Our calculations revealed adequate access to the lateral cavernous sinus, Meckel cave, orbital apex, and middle fossa floor. Cadaveric testing revealed sufficient access to these areas using <10 mm of orbital retraction. Conclusions Our study validates not only the use of computer simulation to plan operative approaches but the feasibility of the lateral retrocanthal approach to the lateral cavernous sinus.

Transnasal endoscopic surgery has remained at the forefront of surgical management of sinogenic complications involving the frontal sinus, orbit, and anterior skull base. However, the difficulty in accessing certain areas of these anatomical regions can potentially limit its use. Transorbital neuroendoscopic surgery (TONES) was recently introduced to transgress the limits of transnasal endoscopic surgery; the access that it provides could add additional surgical pathways for treating sinogenic complications involving the frontal sinus, orbit, and anterior cranial fossa. We describe a prospective series of 13 patients who underwent TONES for the management of various sinogenic complications, including epidural abscess, orbital abscess, and fronto-orbital mucocele or mucopyocele, as well as subperiosteal abscess presenting with orbital apex syndrome. The primary outcome measurement was the efficacy of TONES in treating these pathologies. TONES provided effective access to the frontal sinus, orbit, and the anterior cranial fossa. All patients demonstrated postoperative resolution of initial clinical symptoms with well-hidden surgical scars. There were no ophthalmologic complications or recurrence of pathology. Based on our experience, TONES appears to provide a valuable addition to the current surgical armamentarium for treating selected complications of sinusitis.

Objectives: To describe an anatomic and clinical outcome study of transorbital neuroendoscopic surgical (TONES) for the repair of complex anterior cranial fossa (ACF) cerebrospinal fluid (CSF) leaks.

Design: Anatomic cadaver investigation and clinical outcomes evaluation.

Methods: An anatomic cadaver study was undertaken to determine the anatomic feasibility of the TONES approaches for repair of CSF leaks, and determine the optimal approaches for these repairs. A targeted outcome analysis was performed on 10 consecutive patients who underwent 12 ACF CSF leak repairs by TONES.

Results: The cadaver study demonstrated that the entire ACF can be accessed by TONES. Due to the rise and angulation of the orbital roof above the interorbital ACF, the precaruncular (PC) approach optimal for a coplanar target approach in the interorbital ACF, and the superior lid crease (SLC) trajectory is preferable for procedures involving the supraorbital ACF. There were no complications in the 12 clinical procedures. Fifty percent of the cases were revisions, referred after up to five previous craniotomies and endoscopic procedures; all TONES repairs were successful with a single operation.

Conclusions: The use of TONES to repair ACF CSF leaks was demonstrated to be technically feasible in cadaver and clinical studies. The SLC approach was optimal for supraorbital ACF leaks; the PC approach was preferable for interorbital ACF pathology. TONES was shown to be highly effective for treating complex pathology that was refractory to correction through frontal craniotomy and /or transnasal endoscopy, providing safe, minimally disruptive direct coplanar routes for target approach and manipulation.

Objective: To prospectively evaluate the safety, effectiveness, and utility of orbital and transorbital endoscopic surgery.

Study design: Case series with planned data collection.

Setting: Level 1 trauma center and tertiary academic hospital.

Subjects and methods: Consecutive sample of 107 patients undergoing orbital or transorbital endoscopic operations.

Main outcome measures: Ability to achieve intraoperative goals using endoscopic approach; occurrence of predetermined intraoperative or postoperative complications.

Results: One hundred seven patients (aged 6-83 years) underwent orbital or transorbital endoscopic surgery for 6 different indications. Seven incisions were used. Endoscopic orbitotomies were made through all 4 orbital walls to access surrounding structures. Intraoperative goals were achieved endoscopically in 106 patients. Mean follow-up was 3 months (mean ± SD, 3.0 ± 3.5). No complication was directly related to surgical approach or use of endoscopy. Seventeen complications were detected in 2 categories: persistent diplopia and persistent vision change. No patient had vision loss. No nonfracture patient suffered a complication. Subgroup analysis demonstrated no difference in surgical success rates when compared with transnasal and transantral medial orbital wall and orbital floor repair and cerebrospinal fluid leak repair. Endoscopic visualization was advantageous in several respects: superior visualization and lighting, particularly posterior to the equator of the globe; image magnification; and video monitoring for education and operating room staff involvement. It also facilitated surgical navigation and computer-aided reconstruction.

Conclusion: Orbital and transorbital endoscopy are versatile, effective, and safe approaches useful for addressing diverse urgent and elective problems. In appropriate clinical situations, these procedures may offer better access and visualization than open or transnasal approaches.